The proposed research would use behavioral observation techniques to explore a new Pavlovian appetitive conditioning preparation in which rats exhibit quite different conditioned behavior depending on the physical characteristics of the conditioned stimulus (CS). The research has two goals. First, it would evaluate an orienting response hypothesis for the observed differences in conditioned behavior. This hypothesis assumes that conditioned behavior in this situation represents the interaction of two separate classes of responding: enhancement of the original orienting response specific to each CS, and acquisition of behaviors appropriate to the unconditioned stimulus common to all CSs. Second, it will provide basic parametric data for this conditioning preparation so that subsequent research can use the preparation in confidence. This preparation would be especially valuable because of its large effects of CS characteristics on CR form: since conditioning to different stimulus elements is "labeled" with unique behaviors, new approaches to problems to compound conditioning, stimulus selection, and other issues would be made possible.